The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art to the present invention.
Many cancers are characterized by disruptions in cellular signaling pathways that lead to aberrant control of cellular processes, or to uncontrolled growth and proliferation of cells. These disruptions are often caused by changes in the activity of particular signaling proteins, such as kinases. Among these cancers are solid tumors, like non-small cell lung cancer (NSCLC). NSCLC is the leading cause of cancer death in the United States, and accounts for about 87% of all lung cancers. There are about 151,000 new cases of NSCLC in the United States annually, and it is estimated that over 120,000 patients will die annually from the disease in the United States alone. NSCLC, which comprises three distinct subtypes, is often only detected after it has metastasized, and thus the mortality rate is 75% within two years of diagnosis.
It is known that gene deletions and/or translocations resulting in kinase fusion proteins with aberrant signaling activity can directly lead to certain cancers. For example, it has been demonstrated that the BCR-ABL oncoprotein, a tyrosine kinase fusion protein, is a causative agent in human chronic myelogenous leukemia (CML). The BCR-ABL oncoprotein, which is found in at least 90-95% of CML cases, is generated by the translocation of gene sequences from the c-ABL protein tyrosine kinase on chromosome 9 into BCR sequences on chromosome 22, producing the so-called Philadelphia chromosome. See, e.g. Kurzock et al., N. Engl. J. Med. 319: 990-998 (1988). The translocation is also observed in acute lymphocytic leukemia and NSCLC cases.
EML4-ALK is a fusion-type protein tyrosine kinase that is generated in human non-small-cell lung cancer (NSCLC) and other cancers as a result of a recurrent chromosome inversion, inv (2)(p21p23). EML4 (echinoderm microtubule-associated protein like protein 4) is a cytoplasmic protein with a molecular weight of 120,000, which is highly expressed in the M phase of the cell cycle. The human EML4 gene encodes a polypeptide with 981 amino acids and has 23 exons. The EML4 protein has a basic region at the amino terminus, as with other members of the EML family, and further has carboxyl-terminal WD domains. The function of EML4 in cells is not known. However, according to a recent report, EML4 may participate in microtubule formation.
ALK (Anaplastic Lymphoma Kinaseis receptor tyrosine kinase) is a protein that has a transmembrane domain in the central part, a carboxyl-terminal tyrosine kinase region, and an amino-terminal extracellular domain. The ALK gene has 30 exons and encodes a polypeptide with 1,620 amino acids. The ALK gene has been reported to participate in the development or functioning of the nervous system. Full-length ALK expression has been reported in some cancer cells of ectodermal origin, such as neuroblastoma, glioblastoma, breast cancer, and melanoma.